Here is the full list of all 70 Dragon Cliff achievements.
Slay Bloody Eye
Slay Bone Devil
Obtain invitation of Iron Soldier
Obtain invitation of Fire Spirit
Obtain invitation of Elemental Wizard
Slay Dark Knight
Obtain invitation of Cube
Slay Dark Executor
Slay Corrupted Horn
Obtain invitation of Bun Sister
Obtain invitation of Snow Maiden
Slay Yitchin, the nest of thousand worms
Complete quest 'Immortal Corpse, Shijie Xian'
Obtain invitation of Young Warlock
Obtain invitation of Fire Assassin
Obtain invitation of Night Blade
Slay Demon Skull
Obtain invitation of Warrior
Slay Dragon Servant
Obtain invitation of Red Horn
Obtain invitation of Duelist
Obtain invitation of Fire Player
Obtain invitation of Tough Woman
Slay Blacksmith Wong's Brother
Obtain invitation of Paladin
Slay Blood Stone Beast
Obtain invitation of Chubby Lady
Obtain invitation of Soul Thief
Complete quest 'Farm, farm, farm!'
Slay Purple Orc
Slay Green Orc
Slay Golem
Slay Hydra
Slay Demon Dragon
Complete level one of Imperial Mausoleum
Complete quest 'Evil Books'
Complete quest The undead aristocracy'
Slay Green Orc on 2 star difficulty
Slay Purple Orc on 2 star difficulty
Slay Blood Stone Beast on 2 star difficulty
Slay Blacksmith Wong's Brother on 2 star difficulty
Slay Dragon Servant on 2 star difficulty
Slay Demon Skull on 2 star difficulty
Slay Corrupted Horn on 2 star difficulty
Slay Yitchin, the nest of thousand worms on 2 star difficulty
Slay Dark Executor on 2 star difficulty
Slay Bone Devil on 2 star difficulty
Slay Bloody Eye on 2 star difficulty
Slay Golem on 2 star difficulty
Slay Hydra on 2 star difficulty
Slay Demon Dragon on 2 star difficulty
Complete level one of Imperial Mausoleum on 2 star difficulty
Complete quest 'Immortal Corpse, Shijie Xian' on 2 star difficulty
Complete quest 'Farm, farm, farm!' on 2 star difficulty
Complete quest 'Evil Books' on 2 star difficulty
Complete quest The undead aristocracy' on 2 star difficulty
Obtain invitation of Conjurer
Obtain invitation of Fashion Boy
Obtain invitation of Golden Shaman
Obtain invitation of Tactician
Complete level 100 of Mystic Dimension
Complete level 200 of Mystic Dimension
Complete level 300 of Mystic Dimension
Complete level 400 of Mystic Dimension
Complete level 500 of Mystic Dimension
Complete level 600 of Mystic Dimension
Complete level 700 of Mystic Dimension
Complete level 800 of Mystic Dimension
Complete level 900 of Mystic Dimension
Complete level 1000 of Mystic Dimension